My audio driver's StartDevice callback calls a function twice to instantiate both the topology and wave subdevices:

NTSTATUS InstallSubdevice(IPort **ppIPort, IMiniport **ppIMiniport, DEVICE_OBJECT *pDeviceObject, IRP *pIrp,
    PCWSTR pszMiniportName, REFGUID riidPortClass, REFGUID riidMiniportClass, PFN_FACTORY_METHOD pfnFactoryMethod,
    IUnknown *pIUnkAdapter, IResourceList *pIResourceList)
{
    ASSERT(pszMiniportName);

    DPF_ENTER(("[%s '%S']", __FUNCTION__, pszMiniportName));

    ASSERT(pDeviceObject);

    // Create the PortCls driver object and return an IPort interface
    IPort *pIPort   = nullptr;
    auto   ntStatus = ::PcNewPort(&pIPort, riidPortClass);

    // Create the specified miniport (CMiniportTopology or CMiniportWaveRt) object and return an IMiniport interface
    IMiniport *pIMiniport = nullptr;
    if (NT_SUCCESS(ntStatus))
    {
        ntStatus = pfnFactoryMethod
                       ? pfnFactoryMethod(&pIMiniport, riidMiniportClass, pIUnkAdapter, NonPagedPoolNx) // (CreateInstance call)
                       : ::PcNewMiniport(&pIMiniport, riidMiniportClass);
    }

    // Initialize the audio port driver (calls IMiniportXXX::Init on the miniport)
    if (NT_SUCCESS(ntStatus))
        ntStatus = pIPort->Init(pDeviceObject, pIrp, pIMiniport, pIUnkAdapter, pIResourceList);

I'm getting STATUS_INVALID_PARAMETER back from the pIPort->Init(...) call at the bottom. I've been over each of the parameters in WinDbg multiple times, and I can't find anything wrong with them. I've even tried passing nullptr for pIrp, pIUnkAdapter, and pIResourceList (based upon differences in some of the sample code), but I get the same result.

Could this be due to something else, like a mistake somewhere in my INF file?

SIDE QUESTION: Since the "common adapter" class doesn't seem to need to implement any well-known interfaces other than IUnknown (docs do mention IAdapterObject, but I couldn't find any references to that in docs or examples), why does this API include it? I can't see what PortCls could do with it, other than AddRef/Release it...